Development of a 4-DoF Active Upper Limb Orthosis

In this paper, the designs and manufacturing process of a powered upper limb orthosis are presented. The orthosis is an exoskeleton worn on one arm by the user and fixed to the trunk. The orthosis’ architecture, design, and manufacturing process are presented and discussed. Estimations of the ranges of movement related to daily living activities are presented. The preliminary tests to verify the functionality of the design show encouraging results

Master of Science

thesisHuman motion capture has a wide variety of applications in the entertainment and medical industries. Actors using motion capture devices provide realistic motion inputs for cartoons, virtual reality environments™, and computer and robot animation, resulting in tremendous time and cost savings. Medical applications include range of motion studies to diagnose injuries or identify insurance fraud, biomechanics studies of human performance and calculation of joint stresses, and ergonomics studies of humans in the workplace. There are common problems facing all methods of motion capture: how to attach the device to the individual's limbs, what sensors to use and how to use them, how to transmit data and convert it into a usable form, calibration of the device, data display, user comfort, and device reliability. Even when these problems are addressed, there are limitations in the kinematic model as well as human joint anomalies that make all methods imperfect. Currently, there are optical, magnetic, and exoskeletal devices for motion capture that vary widely in terms of performance, cost and limitations. Considering the likely environment and performance needs of the Sarcos Research Corporation, the SenSuit™ was built as an exoskeletal device. Creation of the SenSuit™ involved overcoming three major hurdles: the soft tissue interface, accurate joint angle measurement, and sensor design. The soft tissue interface is the series of rigid plates that are placed on skeletal landmarks located near the surface of the user's skin. Through appropriate location of the plates, a consistent, stable fit to the skeleton was achieved for users, which enhanced joint angle data. Accurate joint angle measurements were achieved either by aligning sensor rotation centers with approximate joint rotation centers or by computationally transforming the outputs of three degree of freedom sensor clusters located to reduce nonlinearities. A software routine allowed for quick, linear calibration of the individual. Joint angle sensors were designed that were small, linear, robust, and resistant to wear and contaminants. The SenSuit™ has proven itself both comfortable and reliable. It has been thoroughly tested in real-world applications, including real-time driving of graphical and robotic figures, as well as the programming of various robotic figures

Design and Control of an Exoskeletal Rehabilitation Device for Stroke and Spinal Cord Injury Patients

Robotic rehabilitation has gained significant traction in recent years, due to the clinical demonstration of its efficacy in restoring function for upper extremity movements and locomotor skills, demonstrated primarily in stroke populations. In this thesis, I present the design of MAHI Exo-II, a robotic exoskeleton for rehabilitation of the upper extremity after stroke, spinal cord injury, or other brain injuries. The five degree-of-freedom robot enables elbow flexion-extension, forearm pronation-supination, wrist flexion-extension, and radial-ulnar deviation. In the first part of this thesis, hardware design of the system is presented. The device offers several significant design improvements compared to its predecessor, MAHI Exo I. Specifically, issues with backlash and singularities in the wrist mechanism have been resolved, torque output has been increased in the forearm and elbow joints, a passive degree of freedom has been added to allow shoulder abduction thereby improving alignment especially for users who are wheelchairbound, and the hardware now enables simplified and fast swapping of treatment side. These modifications are discussed in the thesis, and results for the range of motion and maximum torque output capabilities of the new design and its predecessor are presented. In the second part of this thesis. I present the modification and implementation of a previously reported linear position and force control to MAHI Exo-II. The modified controller includes three different modes which are designed for use with patients with different levels of severity of injury. These modes either completely assist or resist the patient during the movement. Next, I present the implementation of a previously proposed nonlinear control algorithm in simulation for the forearm and wrist module of MAHI Exo-II. The proposed nonlinear controller aims to provoke a compliant characteristic to the device and assist the patient only as much as needed. Finally, the result of clinical testing of the feasibility of the mechanical design and the efficacy of the control modes with a 28-year-old female SCI patient are presented